Old age or millions of loud noise damages hair cells in the inner ear, which is the common cause of deafness. But researchers found a drug that is believed when injected in that part of the ear could restore hearing.

People have only 15,000 hair cells, which doesn't rejuvenate once damaged as they do in birds and amphibians, Mai Onlinel reported. Cochlear implant is the current sole solution of deafness. This process avoids the disabled part of the ear and induces auditory nerve, which transports sound to the brain.

However, U.S. researchers discovered a mixture of drugs that enable to grow large amounts of new hair cells in the laboratory. The test uses cells from mice, and the scientists will begin human trials in 18 months. They intend to inject drugs into their ears to induce growth of hair cells.

According to Express.co.uk, the researchers presume that it could be easily implemented to humans since the new therapy includes a simple drug exposure. The drugs could be infused into the middle ear spreading beyond a membrane going into the inner ear. In fact, this kind of injection is usually carried out to cure ear infections.

"Hearing loss is a real problem as people get older. It's very much of an unmet need, and this is an entirely new approach." Senior author Professor Robert Langer, of Massachusetts Institute of Technology (MIT) said.

In every six people in the UK, one of them experienced some form of deafness or hearing disability. People start experiencing a hearing problem from losing ear hair cells in old age, but cancer, drugs, and antibiotics can be the cause as well.

The main part affected is the inner ear, within the small shell-like cochlea. This comprises the sensory hair cells essential to distinguish sound waves and transfer their signal to neurons then to the brain.

Restoration of people's hearing is the major goal of growing cells in the study, which was published in the journal Cell Reports. This can be implanted into the inner ear to substitute those were gone. In this, scientists used progenitor cells, which are like stem cells that can mold different parts of the body.